U.S. patent number 5,525,991 [Application Number 08/204,179] was granted by the patent office on 1996-06-11 for mobile object identification system.
This patent grant is currently assigned to Nippondenso Co., Ltd.. Invention is credited to Toshihide Ando, Yoshiyuki Kago, Taisei Katoh, Manabu Matsumoto, Michinaga Nagura, Naoki Tokitsu, Atsushi Watanabe, Mutsushi Yamashita.
United States Patent |
5,525,991 |
Nagura , et al. |
June 11, 1996 |
Mobile object identification system
Abstract
The primary object of the invention is to realize a mobile
object identification system of simple construction and low cost,
in which the responding unit attached to a mobile object writes
data only once when it receives write signals repeatedly in
communication with antenna units. When a tag unit (responding unit)
receives a write signal from a writing antenna unit, it writes data
to the data memory when a completion flag is cleared. When the data
is first written, a control circuit sets the completion flag. Then,
if the tag unit receives additional write signals in the
communication area of the same writing antenna unit, the control
circuit invalidates the data write command on the ground that the
completion flag is set, thereby preventing duplicate data
writing.
Inventors: |
Nagura; Michinaga (Kariya,
JP), Matsumoto; Manabu (Handa, JP), Ando;
Toshihide (Chita-gun, JP), Yamashita; Mutsushi
(Handa, JP), Katoh; Taisei (Toyoake, JP),
Kago; Yoshiyuki (Nishio, JP), Watanabe; Atsushi
(Toyokawa, JP), Tokitsu; Naoki (Kariya,
JP) |
Assignee: |
Nippondenso Co., Ltd. (Kariya,
JP)
|
Family
ID: |
27474126 |
Appl.
No.: |
08/204,179 |
Filed: |
February 24, 1994 |
PCT
Filed: |
June 24, 1993 |
PCT No.: |
PCT/JP93/00858 |
371
Date: |
February 24, 1994 |
102(e)
Date: |
February 24, 1994 |
PCT
Pub. No.: |
W094/00921 |
PCT
Pub. Date: |
January 06, 1994 |
Foreign Application Priority Data
|
|
|
|
|
Jun 25, 1992 [JP] |
|
|
4-167328 |
Jun 25, 1992 [JP] |
|
|
4-167329 |
Jun 25, 1992 [JP] |
|
|
4-167330 |
Dec 14, 1992 [JP] |
|
|
4-333151 |
|
Current U.S.
Class: |
340/10.51;
235/384 |
Current CPC
Class: |
G01S
13/751 (20130101); G01S 13/765 (20130101); G01S
13/767 (20130101); G06K 1/128 (20130101); G06K
7/10059 (20130101); G06K 7/10346 (20130101); G06K
19/0723 (20130101); G06Q 20/341 (20130101); G07B
15/063 (20130101); G07F 7/082 (20130101); G07F
7/1008 (20130101); G08G 1/017 (20130101) |
Current International
Class: |
G01S
13/00 (20060101); G01S 13/75 (20060101); G01S
13/76 (20060101); G08G 1/017 (20060101); G07B
15/00 (20060101); G07F 7/10 (20060101); G06K
19/07 (20060101); G06K 7/10 (20060101); G06K
1/00 (20060101); G06K 1/12 (20060101); G06K
19/073 (20060101); G01S 013/75 (); H04B
001/59 () |
Field of
Search: |
;340/636,825.54,928,825.15,825.32,825.55 ;342/42,44,69 ;235/384
;250/341.1,338.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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|
54-99887 |
|
Aug 1979 |
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JP |
|
58-62784 |
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Apr 1983 |
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JP |
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61-129928 |
|
Jun 1986 |
|
JP |
|
62-243092 |
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Oct 1987 |
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JP |
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62-294347 |
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Dec 1987 |
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JP |
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63-52082 |
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Mar 1988 |
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JP |
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1152599 |
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Jun 1989 |
|
JP |
|
1259484 |
|
Oct 1989 |
|
JP |
|
230652 |
|
Feb 1990 |
|
JP |
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293390 |
|
Apr 1990 |
|
JP |
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2171677 |
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Jul 1990 |
|
JP |
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2208587 |
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Aug 1990 |
|
JP |
|
4123190 |
|
Apr 1992 |
|
JP |
|
Primary Examiner: Lobo; Ian J.
Attorney, Agent or Firm: Cushman, Darby & Cushman
Claims
What is claimed is:
1. A responder which is attached to a movable object for writing
data when receiving a write signal in a communication area of a
writing interrogator and reading and transmitting data when
receiving a read signal in said communication area of a reading
interrogator, as said responder is moved with said movable object,
said responder comprising:
data storage means for storing data;
control means for controlling a process of writing data into said
storage means, and for controlling a process of reading data from
said data storage means; and
status storage means for storing write completion status data when
said control means controls said process of writing data to said
data storage means in response to a first write signal from said
writing interrogator;
said control means invalidating said process of writing data to
said data storage means when said control means receives a second
write signal from said writing interrogator.
2. A communication system for a mobile object identification
system, comprising:
a responder transmitting and receiving signals through a mobile
antenna mounted on a mobile object;
an interrogator transmitting and receiving signals through a
plurality of stationary antennas installed along a moving area of
said mobile object, said plurality of stationary antennas having
respective communication areas which overlap partly in a direction
of movement of said mobile object; and
a control device controlling an operation of said interrogator;
wherein said interrogator includes level judging and signal
selecting means for simultaneously judging respective signal levels
of a plurality of responding signals received respectively by said
plurality of stationary antennas, for selecting one of said
plurality of responding signals, and for outputting said selected
one of said plurality of responding signals.
3. A mobile object identification system, comprising:
a responder mounted on a mobile object and which, when receiving an
interrogatory signal with a first frequency, modulates by a
responding signal an unmodulated carrier wave received after said
interrogatory signal, and which transmits said
responding-signal-modulated carrier wave;
a plurality of interrogators, each of said plurality of
interrogators modulating a respective carrier wave having a
predetermined frequency allocated for respective overlapping
communication areas of each of said plurality of interrogators by a
respective interrogatory signal, each of said plurality of
interrogators transmitting said modulated carrier wave, followed by
an unmodulated carrier wave, to said respective communication area,
adjacent ones of said respective communication areas of said
plurality of interrogators having different carrier frequencies,
and each of said plurality of interrogators receiving a responding
signal from said responder when positioned in said respective
communication area; and
control means for controlling said plurality of interrogators so
that said adjacent ones of said plurality of interrogators transmit
said respective interrogatory signals at different times.
4. An electronic label for a mobile object identification system,
comprising:
a responding circuit for storing vehicle information varying from
vehicle to vehicle, said responding circuit outputting said vehicle
information in response to an interrogatory signal received from an
interrogator; and
a visual information sheet attached on a windshield glass of a
vehicle to face said responding circuit, said visual information
sheet being displayed on said vehicle so as to be seen from an
exterior of said vehicle;
wherein at least said responding circuit is embedded in said
windshield glass of said vehicle.
5. An electronic label for a mobile object identification system,
comprising:
a responding circuit which is embedded in a windshield glass of a
vehicle, said responding circuit storing vehicle information
varying from vehicle to vehicle, and said responding circuit
outputting said vehicle information in response to an interrogatory
signal received from an interrogator;
said responding circuit being placed just above a rear view mirror
of said vehicle and connected to a battery of said vehicle through
a power line.
6. A responder according to claim 1, wherein said control means
invalidates said process of writing data to said data storage means
when said control means receives a second write signal from said
writing interrogator and said write completion status data retained
in said status storage means indicates that said control means
allowed data in response to said first write signal to be written
to said data storage means.
Description
FIELD OF THE INVENTION
The present invention relates to a mobile object identification
system for identifying a responder mounted on a mobile object in a
communication area by transmitting interrogatory signals from an
interrogator to the responder and receiving responding signals from
the responder.
BACKGROUND OF THE INVENTION
A mobile object identification system transmits interrogatory
signals from an interrogator to a responder attached to a mobile
object and receives responding signals from the responder, thereby
identifying the responder. Recently, there has been demand for
mobile object identification systems that can assure accurate
communication between interrogator and responder.
BRIEF SUMMARY OF THE INVENTION
To meet this demand, the first object of the invention (first
invention) is to provide a responder for a mobile object
identification system that, in the communication area of a writing
interrogator, can write data upon receipt of a write signal and
that, in the communication range of a reading interrogator, can
read and transmit necessary data upon receipt of a read signal as
it moves with the mobile object. The responder according to this
invention comprises: data storage means for writing or reading
necessary data; control means for controlling the processing for
writing data to or reading data from the data storage means; and
status storage means for storing the write completion status when
necessary data has been written to the data storage means under
control of the control means, so as to respond to a write signal
received from the writing interrogator. The control means
invalidates the processing for writing data when, with the write
completion status retained in the status storage means, it receives
a write signal from the writing interrogator.
According to the first invention, when the responder of the mobile
object identification system receives a first write signal in the
communication area of the writing interrogator, the control means
writes the necessary data to data storage, and the status storage
means ensures storage of the write completion status data. In this
state, if the responder receives a second write signal from the
writing interrogator, the control means invalidates the signal,
since the write completion status data is already stored.
For various reasons, the mobile object may move slowly or stop in
the communication area of the writing interrogator. In such a case,
the responder attached to the mobile object receives the write
signal repetitively from the writing interrogator. With the
responder of the first invention, since the control means
invalidates processing for writing the second and subsequent write
signals, it allows a write signal to be written only once. Even if
a plurality of responders are positioned in the same communication
area, each responder operates as described above so that a write
signal is written only once in each responder.
The second object of the invention (second invention) is to provide
a mobile object identification system communication complex
comprising: a responder for transmitting/receiving signals through
the mobile antenna mounted on a mobile object; an interrogator for
transmitting/receiving signal through a plurality of stationary
antennas installed along the moving area of the mobile object; and
a control device for controlling operation of the interrogator. The
interrogator includes a level judging circuit to identify the
highest-level responding signal of those received by the stationary
antennas, and a signal selection circuit to selectively output to
the control device the responding signal identified by the level
judging circuit.
According to the communication complex of the second invention, the
interrogator transmits interrogatory signals through the antennas.
When the mobile object enters the communication area, the responder
mounted on the mobile object transmits a responding signal in
response to the interrogatory signal received.
Since the interrogator has the plurality of antennas installed
along the moving area of the mobile object, the responder
communicates with the plurality of antennas simultaneously. The
level judging circuit of the interrogator identifies the
highest-level responding signal of all the signals received by
these antennas, and the level selection circuit selectively outputs
to the control device the responding signal identified by the level
judging circuit, enabling the control device to read the
highest-level responding signal without switching antennas.
The third object of the invention (third invention) is to provide a
mobile object identification system comprising a responder mounted
on a mobile object, which responder, when receiving an
interrogatory signal in a specified frequency band, with a
responding signal, modulates the unmodulated carrier wave received
after the interrogatory signal, and transmits the responding
signal-modulated carrier wave. Each of a plurality of interrogators
modulate, with the interrogatory signal, the carrier wave in the
specified frequency band allocated for each of the communication
areas of the plurality of interrogators, transmit the interrogatory
signal-modulated carrier wave, followed by unmodulated carrier
wave, to the appropriate communication area. Each interrogator also
receives the responding signal from the responder positioned in the
appropriate communication area. A control means controls the
plurality of interrogators so that at least those interrogators
whose communication areas overlap transmit carrier waves in
different frequency bands and transmit interrogatory signals at
different timings.
According to the mobile object identification system of the third
invention, when the responder mounted on the mobile object is in
any one of the plurality of communication areas provided by the
plurality of interrogators, the appropriate interrogator transmits
the interrogatory signal; the responder receives the interrogatory
signal, generating a responding signal in response. The carrier
wave received after the interrogatory signal is then modulated by
the responding signal, and the responder transmits the responding
signal-modulated carrier wave. The interrogator receives this wave,
thereby identifying the responding signal.
When the responder is located in the zone where communication areas
overlap, the corresponding interrogators transmit interrogatory
signals at different frequencies and different timings via the
control means, so that the responder receives one interrogatory
signal from any of the interrogators at a time. Thus, the responder
accepts the interrogatory signal received first, generates a
responding signal which modulates the carrier wave received after
the interrogatory signal, and transmits the responding
signal-modulated carrier wave.
At this time, it is possible that the responding signal-modulated
carrier wave is received by the two interrogators whose
communication areas overlap the appropriate one. Even in such a
case, the responder can communicate with the appropriate
interrogator without radio interference, due to the difference in
frequency of the responding signal-modulated carrier wave from the
frequency allocated for the other interrogator. In addition,
according to the present invention, unlike in conventional cases,
where the communication period is time-shared by multiple
interrogators, radio waves can be transmitted simultaneously in the
zone where communication areas overlap. Consequently, the responder
mounted on the mobile object can communicate with an appropriate
interrogator promptly and accurately, even when moving at high
speed.
The fourth object of the invention (fourth invention) is to provide
an electronic label for the mobile object identification system
comprising: a responding circuit in which is stored vehicle
information such as the frame number (e.g., vehicle identification
number (VIN)), and which outputs the vehicle information in
response to an interrogatory signal received from an interrogator.
Information given on the surface of the electronic label is that
found on such labels that are legally required to be attached to a
vehicle.
When an interrogatory signal is sent from an external interrogator
to the vehicle to which the electronic label of the fourth
invention is attached, the responding circuit receives the
interrogatory signal, and returns the preliminarily loaded vehicle
information. Therefore, the vehicle information need not be checked
visually. Even if the vehicle is often running past without
stopping, the vehicle information can be recognized easily.
When the electronic label bears on the surface the same particulars
as given on a mandatory vehicle inspection label or a regular check
and maintenance label legally attached to the windshield glass of
the vehicle, the electronic label can be attached to the windshield
glass without causing any problems. This position is also the
optimum for electronic label reception of interrogatory signals
transmitted from ahead of or above the vehicle. For a vehicle to be
driven on public roads, it is legally required to have such vehicle
inspection label or regular check and maintenance label attached.
Therefore, such a label is not to be removed. Accordingly, the
information read from the electronic label attached to the
windshield glass of a vehicle can be considered as information
specific to the vehicle.
The fifth object of the invention (fifth invention) is to provide
another electronic label for the mobile object identification
system comprising: a responding circuit in which is stored vehicle
information such as the frame number and which outputs the vehicle
information in response to an interrogatory signal received from an
interrogator, the responding circuit being embedded in the
windshield or window glass.
When an interrogatory signal is sent from an external interrogator
to a vehicle equipped with the electronic label of the fifth
invention, the responding circuit embedded in the window glass
receives the interrogatory signal and returns the preliminarily
written vehicle information. Therefore, as with the fourth
invention, the vehicle information need not be checked visually,
and can be recognized easily if the vehicle is running past without
stopping.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow chart of the control program for an embodiment of
the responder according to the first invention;
FIG. 2 is a schematic view explaining the general concept of the
first invention;
FIG. 3 is a block diagram showing the electrical construction of
the first invention;
FIG. 4 is a schematic view explaining conventional art as opposed
to the first invention;
FIG. 5 is a schematic view explaining another conventional device
as opposed to the first invention;
FIG. 6 is a schematic view explaining the disadvantages of the
conventional art as opposed to the first invention;
FIG. 7 is a block diagram showing the construction of the
interrogator used in an embodiment of the communication complex
according to the second invention;
FIG. 8 is a block diagram of the responder used in the second
invention;
FIG. 9 is a schematic view explaining the general concept of the
second invention;
FIGS. 10A to 10C are a chart showing change in signal level of the
responding signals by the second invention as a mobile object is
moving;
FIG. 11 is a schematic view explaining the general concept of the
mobile object identification system according to the third
invention;
FIG. 12 is a perspective view showing the general appearance of the
third invention;
FIG. 13 is a block diagram showing the electrical construction of
the third invention;
FIG. 14 is a chart showing the frequency characteristics of the
interrogator and responder of the third invention;
FIGS. 15A to 15E are a timing chart of interrogatory signal outputs
of the third invention;
FIG. 16 is a schematic view explaining an operation of the third
invention;
FIG. 17 is a schematic view explaining another operation of the
third invention;
FIG. 18 is a schematic view explaining the disadvantage of
conventional art as opposed to the third invention;
FIG. 19 is a schematic view explaining the disadvantage of another
conventional device as opposed to the third invention;
FIG. 20 is a general perspective view showing an embodiment of the
electronic label according to the fourth invention;
FIG. 21 is a perspective view showing an example of the actual
application of the fourth invention;
FIG. 22 is a diagram showing the electrical construction of the
responding circuit of the fourth invention;
FIG. 23 is an electric circuit diagram of the interrogator for the
fourth invention;
FIG. 24 is a schematic view explaining an example of the actual
application of the fourth invention to a toll road accounting
system;
FIG. 25 is a schematic view explaining an example of actual
application of the fourth invention to an incoming/outgoing vehicle
management system of a parking lot;
FIG. 26 is a schematic view explaining an example of the actual
application of the fourth invention to a regular customer sensing
system;
FIG. 27 is a general view of the windshield glass of a vehicle
incorporating the responding circuit of the electronic label of the
fifth invention, as viewed from inside the vehicle;
FIG. 28 is a schematic view showing the general construction of the
responding circuit of the fifth invention;
FIG. 29 is a general view of the windshield glass of a vehicle
incorporating the responding circuit of the fifth invention
connected to another information processor, as viewed from inside
the vehicle;
FIGS. 30A to 30C are sectional views of window glass for explaining
the method of embedding the responding circuit of the fifth
invention in the window glass;
FIG. 31 is a diagram showing the general electrical construction of
another embodiment of the fifth invention, concerning the window
glass that incorporates the responding circuit;
FIG. 32 is a general view of the windshield glass of a vehicle
incorporating the responding circuit of the second embodiment of
the fifth invention, as viewed from inside the vehicle; and
FIG. 33 is a circuit diagram for explaining the memory in the RF
processing IC of the information processor.
BEST MODE FOR CARRYING OUT THE INVENTION
Prior to explaining the first invention, the conventional art as
opposed to the first invention and its problems will be described
in detail in the following.
A mobile object identification system has many applications, one of
which is in the system for managing unmanned trucks in a factory.
This system comprises a tag unit mounted as a responding unit on
each unmanned truck, and antenna units installed along the passage
of unmanned trucks to provide communication areas for communication
with tag units. Each tag unit of this system includes a memory for
storing various data, such as the identification code, quantities
and destinations of the articles being transported by the unmanned
truck. This memory is designed to enable readout of stored data and
write-in of new data, as necessary.
Each antenna unit is designed to transmit a carrier wave of
specified frequency as modulated by an interrogatory signal, and
then an unmodulated carrier wave to its communication area. As an
unmanned truck moves, the tag unit attached to the truck enters a
communication area and receives an interrogatory signal. The tag
unit then generates a responding signal containing various data
such as article identification code, to answer the interrogatory
signal, via a responding signal, modulates the unmodulated carrier
wave received following the interrogatory signal, and transmits the
responding signal-modulated carrier.
The antenna unit receives the responding signal, by which it
identifies the tag unit of the unmanned truck passing through the
communication area, and recognizes the articles being carried by
the truck. According to this information, the antenna unit stores
new data and/or controls the operation of the unmanned truck, as
necessary.
Some of such conventional mobile object identification systems use
a data memory composed of nonvolatile memory such as EEPROM, for
the responding unit. Generally, a significant amount of time is
needed to write data to a nonvolatile memory. When the
interrogatory signal from an antenna unit includes a data write
command, therefore, the processing for writing data to the data
memory takes an extended time. When the unmanned truck is moving at
a high speed, the tag unit could therefore pass through the
communication area before it can read data written to its data
memory and send it to the interrogating unit, thus hampering
accurate communication.
One conventional device attempts to solve this problem with a
mobile object identification system in which an antenna unit is
divided into a writing antenna unit 10A and a reading antenna unit
12A, which are arranged in that order along the passage 16A of an
unmanned truck 14A, as illustrated in FIG. 4. The writing antenna
unit 10A transmits write signals to the unmanned truck 14A in the
communication area 18A, and the reading antenna unit 12A, installed
at a downstream position, transmits read signals the unmanned truck
14A in the communication area 20A. Therefore, if the tag unit 22A,
attached to the unmanned truck 14A, takes time in writing data to
its data memory, tag unit 22A can complete the processing for
writing data before it enters the communication area 20A of the
reading antenna unit 12A. In other words, if the unmanned truck 14A
is moving at a high speed, the system can identify the truck
through accurate communication between the tag unit and antenna
units.
However, this conventional art also has a drawback. The unmanned
truck 14A may stop in the communication area 18A of the writing
antenna unit 10A for a certain reason. In such a case, the tag unit
22A attached to the unmanned truck 14A repeatedly receives a write
signal transmitted from the writing antenna unit 10A. If the write
signal includes a write command for such data as the number of
transits, the number of transits will be written and updated every
time the write signal is received. Consequently, the wrong number
of transits is stored in the tag unit 22A.
The system shown in FIG. 5 solves this problem. According to this
arrangement, object detectors 24Aa, 24Ab, 26Aa and 26Ab are
installed before and after the antenna units 10A and 12A,
respectively, to detect an object. That is, these detectors detect
the tag unit 22A if it is in the communication area 18A or 20A of
the antenna unit 10A or 12A. With this arrangement, the system
calculates that the unmanned truck 14A exists in the communication
area 18A or 20A for the period from the time when it is detected by
the object detector 24Aa or 26Aa to the time when it is detected by
the object detector 24Ab or 26Ab. Therefore, the system with this
arrangement can solve the above-mentioned problem by controlling
antenna unit 10A or 12A to transmit a write signal only once, when
the unmanned truck 14A enters and stays in the communication area
18A or 20A.
This arrangement, however, also has a drawback. There is no problem
as long as unmanned trucks 14A with tag units 22A pass one by one
through the communication area 18A or 20A. However, two unmanned
trucks 14A may pass through the communication area 18A or 20A
simultaneously, as shown in FIG. 6. In such a case, since the
antenna unit 10A or 12A is controlled to transmit a write signal
only once, it transmits a write signal to the tag unit 22A entering
the communication area 18A or 20A first, but not to the tag units
22A entering the communication area later.
If the antenna unit 10A or 12A transmits a write signal two times
when the object detector 24Aa or 26Aa detects two unmanned trucks
14A in the communication area 18A or 20A, the tag unit 22A entering
the communication area first will receive the write signal two
times, resulting in duplicate writing.
The first invention has solved the above-mentioned problems of the
conventional arts. An embodiment of the first invention is
described in detail with reference to FIGS. 1 through 3 below. In
this embodiment, the first invention is applied to a tag unit for
use in the communication system for unmanned trucks.
In FIG. 2, that shows the general concept of the first invention,
an unmanned truck 30A as a mobile object is controlled by a control
device (not shown) to move along a passage 32A. The truck 30A
loaded with articles is expected to run along the passage 32A in
the direction of arrows toward a specified destination.
A writing antenna unit 36A providing a communication area 34A, and
a reading antenna unit 40A providing a communication area 38A are
installed in that order at specified adjacent positions along the
passage 32A. A writing antenna unit 44A providing a communication
area 42A and a reading antenna unit 48A providing a communication
area 46A are also installed in that order at specified adjacent
positions along the passage 32A downstream from the antenna units
36A and 40A. Accordingly, when the unmanned truck 30A runs along
the passage 32A, it passes through the communication areas 34A,
38A, 42A and 46A in that order.
The unmanned truck 30A is provided with a tag unit 50A as a
responder of the present invention, so that it communicates with
the antenna units 36A, 40A, 44A and 48A in the communication areas
34A, 38A, 42A and 46A, respectively, as will be described
later.
Each of the antenna units 36A, 40A, 44A and 48A comprises batch
antennas realized by microstrip lines formed on PC boards; these
batch antennas are arranged in multiple groupings as an array
antenna to improve the directivity and to accommodate long-distance
communication. To transmit write/read signals, the antenna units
36A, 40A, 44A and 48A use semi-microwaves in a frequency band of,
for instance, 2.45 GHz as carrier waves.
The antenna units 36A, 40A, 44A and 48A transmit the
above-mentioned carrier waves as modulated by a write/read signal
during the write/read signal transmission period, and transmit
unmodulated carrier waves during the other period. While the
antenna unit 36A, 40A, 44A or 48A is transmitting an unmodulated
carrier wave, it receives radio waves sent from the tag unit 50A in
the communication area 34A, 38A, 42A or 46A.
FIG. 3 shows the electrical construction of the tag unit 50A, a
control circuit 52A includes a CPU, ROM and RAM as control means.
The control circuit 52A stores a control program (described later)
for controlling communication as well as for use as a status
storage means (also described later). An antenna 54A is composed
of, for example, batch antennas realized by microstrip lines formed
on PC boards.
The antenna 54A is connected to the control circuit 52A in two
ways: through a radio wave detector 56A and through a demodulation
circuit 58A. The antenna 54A is grounded via a switch circuit 60A.
The control pin of the switch circuit 60A is connected to the
control circuit 52A through a modulation circuit 62A. The radio
wave detector 56A detects the radio wave received by the antenna
54A, and outputs the detection data to the control circuit 52A. The
demodulation circuit 58A demodulates the radio wave received by the
antenna 54A, and outputs the demodulated wave as a reception signal
to the control circuit 52A. The modulation circuit 62A modulates
the carrier wave by opening/closing the switch circuit 60A
according to the responding signal output from the control circuit
52A.
A data memory 64A connected to the control circuit 52A forms data
storage means. The data memory 64A is composed of a nonvolatile
memory such as an EEPROM. The control circuit 52A executes the
processing for writing or reading various data into or out of the
data memory 64A as required. All these circuits of the tag unit 50A
are fed with power by a battery (not shown).
The operation of this embodiment of the first invention is
described with reference to the flow chart of FIG. 1. When power is
supplied, the control circuit 52A of the tag unit 50A starts
running the communication control program shown in FIG. 1.
Specifically, after initialization (step S1), the control circuit
52A is put in the wait state until it receives a radio wave in step
S2. In the above initialization step, various registers and flags
are cleared for initial setting. The completion flag F, as the
status storage means, is also cleared in step S1 (F.rarw.0).
When the unmanned truck 30A moves into the communication area 34A
of the writing antenna unit 36A, the antenna 54A of the tag unit
50A receives a write signal transmitted from the writing antenna
unit 36A. The radio wave detector 56A detects this write signal,
and outputs a detection signal to the control circuit 52A. Based on
the detection signal, a control circuit 52A makes a judgment of
"YES" in step S2, and advances the program to step S3, to check if
the radio wave received is a write signal. Since the control
circuit 52A receives a reception signal as opposed to the write
signal from the demodulation circuit 58A, it makes the judgment for
"YES" in step S3, and advances the program to step S4.
In step S4, the control circuit 52A checks if the completion flag F
has been set. Since the completion flag F has not yet been set
(F=0), the control circuit 52A makes a judgment of "NO", and
advances the program to step S5 where necessary data is written to
the data memory 64A. Then, after setting the completion flag F
(F.rarw.1) in step S6, the program returns to step S2.
The data writing process in step S5 takes longer than other
processing. Therefore, if the unmanned truck 30A is moving at
ordinary speed, the tag unit 50A may complete data writing by the
time the unmanned truck 30A leaves the communication area 34A of
the writing antenna unit 36A.
If the unmanned truck 30A is moving at low speed, the tag unit 50A
may still be in the communication area 34A of the writing antenna
unit 36A when it has completed data writing. In such a case, the
tag unit 50A receives a write signal again. However, when the
program proceeds through steps S2 and S3 to step S4, the control
circuit 52A makes the judgment of "NO" because the completion flag
F has already been set (F=1), and the program is advanced to step
S7. In step S7, since the write signal received the second time is
transmitted from the same writing antenna unit that sent the first
write signal, the control circuit 52A makes the judgment of "YES,"
and the program returns to step S2. In other words, since data
writing is already executed, the control circuit 52A invalidates
the second or subsequent write data.
When the unmanned truck 30A enters the communication area 38A of
the reading antenna unit 40A, the tag unit 50A operates as follows.
The control circuit 52A runs the program through step S2 to step S3
in the same procedure as already described, makes the judgment of
"NO", and advances the program to step S8. Since the control
circuit 52A has received a read signal from the demodulation
circuit 58A, it makes the judgment of "YES" in step S8. The program
is advanced to the step S9 where the control circuit 52A carries
out the data reading process. After the completion flag F is
cleared (F.rarw.0) in step S10, the program returns to step S2.
By the data reading process in step S9, the control circuit 52A
reads to check data recorded, for example, by the write processing
in the data memory 64A, for transmission to the reading antenna
unit 40A. To transmit the data thus read, the control circuit 52A
sends it as a responding signal to the modulation circuit 62A,
which carries out modulation using the responding signal, and
controls the ON/OFF state of the switch circuit 60A.
The unmodulated carrier wave sent from the reading antenna unit 40A
and received by the antenna 54A is thus reflected or absorbed, and
transmitted back to the reading antenna unit 40A. The reading
antenna unit 40A receives the radio wave transmitted from the
communication area 38A while it is sending an unmodulated carrier
wave. The radio wave thus received is demodulated to obtain a
responding signal.
In step S8, if the radio wave received by the antenna 54A is
neither a write signal nor a read signal, the control circuit 52A
makes the judgment of "NO," assuming that the radio wave is
transmitted from a source other than the antenna unit 36A or 40A.
The program then returns to the step S2.
If the unmanned truck 30A stops in the communication area 34A of
the writing antenna unit 36A for some reason, the tag unit 50A will
receive a write signal repeatedly. According to the present
invention, once the control circuit 52A has carried out the data
writing process, it invalidates the second and subsequent write
signals, and does not conduct data writing any more. Therefore, the
problem of duplicate data writing does not occur.
If more than one unmanned truck 30A are positioned in the
communication area 34A each, receiving a write signal repeatedly
from the writing antenna unit 36A, the tag unit 50A of each
unmanned truck 30A carries out the data writing process only once,
due to the above-mentioned means of the control circuit 52A.
According to the present invention, the unmanned truck 30A is
controlled to pass through the communication area 34A of the
writing antenna unit 36A prior to the communication area 38A of the
reading antenna unit 40A. Normally, therefore, as the unmanned
truck 30A runs through the passage and moves out of the
communication area 38A, the completion flag F is set in step S6 and
cleared in step S10 by the control circuit 52A. Accordingly, when
the unmanned truck 30A enters the communication area 42A of another
writing antenna unit 44A, the tag unit 50A carries out the data
writing process only once.
However, if more than one unmanned truck 30A are running in
parallel through, for example, the communication area 38A of the
reading antenna unit 40A, it is possible that the tag unit 50A of a
truck behind the other truck does not receive a read signal sent
from the reading antenna unit 40A.
When the unmanned truck 30A that has received a read signal in the
communication area 38A enters the communication area 42A of the
writing antenna unit 44A and receives a write signal there, the
control circuit 52A of the tag unit 50A carries out the data
writing process as follows. The program is advanced through steps
S2 and S3 to step S4. Since the completion flag F is not cleared
(F=1), the control circuit 52A makes the judgment of "YES" in step
S4, and advances the program to step S7. Since the tag unit 50A
receives a write signal from the writing antenna unit 44A and not
from the writing antenna unit 36A, the control circuit 52A makes
the judgment of "NO" in step S7 and advances the program to step S5
where data is written.
Thus, according to this invention, when the tag unit 50A receives a
write signal from the writing antenna unit 36A or 44A, the control
circuit 52A executes a data writing process, and sets the
completion flag F to invalidate any write process by the second or
subsequent write signal, thereby preventing duplicate data writing
to the data memory 64A. Even if more than one tag unit 50A exist in
the communication area 34A or 42A, each tag unit 50A carries out
the data writing process only once.
In addition, according to the present invention, the control
circuit 52A checks in step S7 if the write signal received has been
sent from the same writing antenna unit as the last write signal,
and writes data if it makes the judgment of "NO". Therefore, even
if the tag unit 50A has not received a read signal from the reading
antenna unit 40A or 48A, it can write data without fail when it
receives a write signal.
In the above-mentioned embodiment of the first invention, the data
memory 64A uses an EEPROM as data storage. A battery-backup RAM or
other memory, such as a so-called IC card, can be used instead of
the EEPROM without departing from the spirit of the present
invention.
In the above embodiment, the invention is applied to the tag unit
for the system of identifying unmanned trucks. The invention is
also applicable to the responding unit of any other mobile object
identification system. For example, it may be applied to the tag
unit for the process control system in a factory to control
production by attaching the tag unit to each product in the line.
It is also applicable to the ID card for a system of managing
persons entering/exiting a room.
Now, prior to explaining the second invention, the conventional art
as opposed to the second invention and its problems will be
described in detail in the following.
various communication complexes have been in operation for mobile
object identification systems. A typical example is a complex in
which an interrogator transmits an interrogatory signal to
communicate with a responder attached to each product being carried
on a conveyor line, receives a responding signal sent from the
responder, and outputs it to a control device for data
processing.
In particular, the interrogator sends an interrogatory signal
through an antenna. When a mobile object enters the communication
area, the responder attached to the mobile object receives the
interrogatory signal through an antenna, and transmits a signal in
response to the interrogatory signal. The interrogator receives the
responding signal and outputs it to the control device which
processes the responding signal, and sends the processed data to a
host computer when necessary.
Recently, the quantity of communication data to be handled by such
a communication system has been expanding with the increase in
operating speed of conveyor lines, causing communication time
shortage. Conventionally, this problem is overcome by installing
multiple antennas of the interrogator along the moving passage of
products and outputting a responding signal from each of the
antennas to the control device. The control device selects the
antenna receiving the highest level responding signal.
With the above-mentioned conventional method, however, the control
device is required to switch antennas while reading the responding
signals output from the interrogator. During the antenna switching
period, the control device cannot read a responding signal, so data
communication is interrupted.
The second invention has solved the above-mentioned problems of the
conventional art. An embodiment of the second invention will be
described in detail below.
FIG. 9, that shows the general concept of the second invention. An
interrogator 10B has a first stationary antenna 12B and a second
stationary antenna 14B, and transmits interrogatory signals
selectively through the first and second stationary antennas 12B
and 14B. A responder 18B is attached to a mobile object 16B. The
first and second stationary antennas 12B and 14B are installed
along the moving area of the mobile object 16B. The communication
area of each of the stationary antennas 12B and 14B is indicated by
the chain double-dashed line. The interrogator 10B can communicate
with the responder 18B when the mobile object 16B is positioned in
either of the communication areas.
The communication areas of the first and second stationary antennas
12B and 14B overlap. The interrogator 10B is designed to transmit
interrogatory signals as controlled by a control device 20B, and to
output responding signals received from the responder 18B to the
control device 20B.
FIG. 7 shows the construction of the interrogator 10B, the
interrogator 10B is connected to the control device 20B through an
input pin 10Ba and an output pin 10Bb. The interrogator 10B
comprises a level judging circuit 22B, a signal selection circuit
24B and a demodulator 26B in addition to the first and second
stationary antennas 12B and 14B.
Since the first and second stationary antennas 12B and 14B are of
the same construction, the first stationary antenna 12B alone will
be described in the following, with the description for the second
stationary antenna 14B omitted. The first stationary antenna 12B
comprises a modulator 28B, an oscillator 30B, a circulator 32B, a
detector 36B and a microstrip antenna 34B. When an interrogatory
signal is input from the control device 20B through the input pin
10Ba, the modulator 28B modulates the interrogatory signal by a
carrier signal given from the oscillator 30B, and outputs the
modulated signal through the circulator 32B to the microstrip
antenna 34B. When a responding signal is received by the microstrip
antenna 34B, the detector 36B detects the signal through the
circulator 32B, and outputs it to the level judging circuit
22B.
The level judging circuit 22B is designed to receive responding
signals from both first and second stationary antennas 12B and 14B.
The circuit 22B judges the signal level of each responding signal
received, to identify the higher level responding signal, and sends
the judgment result to the signal selection circuit 24B. The signal
selection circuit 24B is also designed to receive responding
signals from both first and second stationary antennas 12B and 14B.
Based on the judgment result from the level-judging circuit 22B,
the signal selection circuit 24B selects the higher level
responding signal, and outputs it to the control device 20B through
the demodulator 26B and the output pin 10Bb.
The control device 20B controls commands to be output from the
interrogator 10B to the responder 18B, and the operation time of
the interrogator 10B. In addition, the control device 20B processes
data received from the responder 18B, and outputs processed data to
a host computer (not shown) or a display unit (not shown) as
necessary.
FIG. 8 shows the construction of the responder 18B. The
interrogatory signal received by a mobile antenna 40B is input
through a detector 42B to a control unit 38B. The mobile antenna
40B is composed of a microstrip antenna. The control unit 38B
outputs a responding signal in reply to the interrogatory signal to
the microstrip antenna 40B through a modulator 44B which modulates
the responding signal. In addition, the control unit 38B
interchanges data with a data memory 46B. Each component of the
responder 18B is fed with power by a battery 48B.
Now, the operation of the second invention, having the
above-mentioned construction, will be described.
The control device 20B outputs interrogatory signals intermittently
to the interrogator 10B, so that the first and second stationary
antennas 12B and 14B transmit the interrogatory signals.
When the mobile object 16B enters the communication area of the
first stationary antenna 12B, the responder 18B attached to the
mobile object 16B receives an interrogatory signal through the
mobile antenna 40B. The responder 18B then transmits a responding
signal, indicating its own identification number, through the
mobile antenna 40B. The first stationary antenna 12B of the
interrogator 10B receives the responding signal, and outputs it
through the detector 36B to the level judging circuit 22B.
At this time, the responding signal from the responder 18B is also
received by the second stationary antenna 14B and input to the
level judging circuit 22B. However, the responding signal from the
second stationary antenna 14B has lower signal level than the
responding signal from the first stationary antenna 12B.
Accordingly, the level judging circuit 22B reckons that the
responding signal input from the first stationary antenna 12B is
higher, and outputs this result to the signal selection circuit
24B. Based on this result, the signal selection circuit 24B selects
the responding signal from the first stationary antenna 12B, and
outputs it to the demodulator 26B. The demodulator 26B demodulates
the responding signal to obtain the identification number, and
outputs it to the control device 20B.
The control device 20B checks if the identification number is
appropriate. If it is, the control device 20B outputs an
interrogatory signal containing a data write command or a data read
command through the first and second stationary antennas 12B and
14B to communicate with the responder 18B.
The signal level of the responding signal received by the first
stationary antenna 12B and input to the control device 20B changes
as the mobile object 16B moves. FIG. 10A shows this change in the
signal level.
As the mobile object 16B moves and enters the overlapping zone of
the communication areas of the first and second stationary antennas
12B and 14B, the signal level of the responding signal from the
second stationary antenna 14B becomes higher than that from the
first stationary antenna 12B (at the timing indicated by "A") as
shown by FIG. 10B. Then, the signal selection circuit 24B selects
as shown by FIG. 10C the responding signal received from the second
stationary antenna 14B, according to the instruction given by the
level judging circuit 22B, and outputs the signal to the control
device 20B. Accordingly, after the timing "A," the control device
20B controls data communication based on the responding signal from
the second stationary antenna 14B.
According to this invention, as mentioned above, the level judging
circuit 22B and signal selection circuit 24B enable the
interrogator 10B to output to the control device 20B the higher
level responding signal of the two signals received by the first
and second stationary antennas 12B and 14B. Therefore, although the
responding signals received by the first and second stationary
antennas 12B and 14B change as the mobile object 16B moves, the
control device 20B always receives the higher level responding
signal.
Thus, unlike the conventional communication system in which a
control device is provided with a means for selecting one of
several stationary antennas, the control device 20B of the
communication system according to the present invention does not
contain an antenna-switching means. Consequently, communication
between the interrogator 10B and the responder 18B can never be
interrupted by an antenna-switching operation.
Before the mobile object identification equipment of the third
invention is explained, the conventional art as opposed to the
third invention and their problems will be described in detail in
the following.
The mobile object identification system has many applications, one
of which is for unmanned trucks in a factory. This system comprises
a tag unit mounted as a responding unit on each unmanned truck, and
antenna units installed along the route of .unmanned trucks to
provide areas for communication with tag units. The tag unit of
this system includes a memory to store various data, such as the
identification code, quantities and destination of the articles
being transported by the unmanned truck. This memory is designed to
allow the stored data to be read, and new data to be written as
necessary.
Each antenna unit is designed to transmit a carrier wave of a
specified frequency as modulated by an interrogatory signal, and
then an unmodulated carrier wave to its communication area. When an
unmanned truck enters the communication area, the tag unit attached
to the truck receives an interrogatory signal. The tag unit then
generates a responding signal for various data, such as the article
identification code, to answer the interrogatory signal, modulates
the unmodulated carrier wave received following the interrogatory
signal, using the responding signal, and transmits the responding
signal-modulated carrier wave.
The antenna unit receives the responding signal, which enables the
unit to identify the tag unit of the unmanned truck passing through
its communication area, determine the articles being carried by the
truck, store new data and/or control unmanned truck operation.
If unmanned trucks are allowed to move in a large area, it is
necessary to set a wide communication area to cover the large
moving area. In the conventional art, this requirement is met by
dividing the wide communication area into blocks and installing a
plurality of antenna units to cover the blocks.
However, if the antenna units 10C and 12C are arranged so that the
communication areas 14C and 16C overlap, as shown in FIG. 18, wave
interference can occur. Specifically, if an unmanned truck 20C
enters the overlapping zone 18C (in the direction indicated by the
arrow), the tag unit 22C attached to the unmanned truck 20C will
receive two interrogatory signals transmitted from the antenna
units 10C and 12C. In such a case, the two signals interfere with
each other, possibly disabling the tag unit 22C for
communication.
To avoid this problem, the antenna units 10C and 12C may be
arranged so that the communication areas 14C and 16C do not
overlap, as shown in FIG. 19. However, this arrangement forms a
dead zone for communication between communication areas 14C and
16C. If an unmanned truck 20C enters this dead zone, the tag unit
22C of the truck 20C will not be able to communicate through either
of the antenna units 10C and 12C.
The invention disclosed in the Japanese Patent Provisional
Publication No. 93390/1990 solves these problems by the following
method. When a wide communication area is to be covered by a
plurality of antenna units, the antenna units are allocated
different communication periods. As a result, if the antenna units
are arranged so that their communication areas overlap, tag units
can communicate through the antenna units without wave
interference.
However, when different communication periods are allocated to each
of the several antenna units, that is, when the communication
period is time-shared by the antenna units, each antenna unit can
be used for communication only during the allocated period. If the
system involves a large number of antenna units, the cycle of the
communication period for each antenna unit will be long. For the
tag unit of an unmanned truck to communicate properly while it is
running in the communication area, a short communication period
must be allocated to each antenna unit, or the unmanned truck must
be driven at a limited speed.
The third invention has solved the above problems. An embodiment of
the third invention will be described in detail below, with
reference to FIGS. 11 through 17. In this embodiment, the third
invention is applied to the identification system for unmanned
trucks.
In FIG. 12, showing the general appearance of the third invention,
the motion of an unmanned truck 30C as a mobile object is
controlled along a specified runway 32C. A gate 34C is located at
the specified position of the runway 32C, to identify each unmanned
truck 30C.
The gate 34C is installed astride the runway 32C, and has a
plurality of antenna units, e.g., five antenna units 36Ca through
36Ce, in portions above the runway 32C. The five antenna units 36Ca
through 36Ce provide communication areas 38Ca through 38Ce,
respectively, obliquely downward to the runway 32C. Of the
communication areas 38Ca through 38Ce, the adjacent ones overlap
each other as shown in FIG. 11, which explains the general concept
of the third invention. The overlapping zones are denoted 40Ca,
40Cb, 40Cc and 40Cd, respectively.
Referring to FIG. 11, the antenna units 36Ca through 36Ce are
connected to a controller 42C. The controller 42C not only controls
data transmission/reception of the antenna units 36Ca through 36Ce
but also sends communication data to and receives such data from a
signal processor 44C, which may be a host computer. Each unmanned
truck 30C has a tag unit 46C as a responding unit storing various
data. When an unmanned truck 30C passes through the gate 34C, this
tag unit 46C communicates with one of the antenna units 36Ca
through 36Ce, as will be described later.
FIG. 13 shows the electrical construction of the invention. The
construction of the antenna unit 36Ca is described. The antenna
unit 36Ca comprises an antenna 48C for transmitting/receiving
signals, a modulation circuit 50C, an oscillator 52C, a circulator
54C, a mixer 58C, and a reception circuit 56C.
The antenna 48C is composed of batch antennas realized by
microstrip lines formed on PC boards; these batch antennas are
arranged in multiples to form an array antenna for improving
directivity and to accommodate long-distance communication.
The modulation circuit 50C modulates carrier wave with a frequency
of f1 (generated by the oscillator 52C) by an interrogatory signal
from the controller 42C, and outputs the modulated signal to the
antenna 48C through the circulator 54C. A specified frequency band
of, e.g., 2.45 GHz is allocated for the system of this invention so
that semi-microwaves in this frequency band are output as carrier
waves. The oscillator 52C outputs semi-microwaves at a frequency of
f1 in this frequency band. The antenna 48C is adapted to
selectively receive only radio waves with a limited frequency of f1
set by the oscillator 52C.
The reception circuit 56, which carries out signal processing such
as demodulation, is connected to the mixer 58C. The mixer 58C
receives not only carrier waves from the oscillator 52C but also
radio waves as opposed to a responding signal from the antenna 48C
through the circulator 54C. The carrier and radio waves as opposed
to a responding signal are synthesized by the mixer 58C and input
to the reception circuit 56C where the synthesized signal is
demodulated to obtain a responding signal. The demodulated
responding signal is output to the controller 42C.
The antenna units 36Cb through 36Ce are the same in construction as
the antenna unit 36Ca, except that the oscillation frequency of the
oscillator 52C is different in each antenna unit. Specifically,
while the oscillation frequency of the oscillator 52C for the
antenna unit 36Ca is set at f1, the oscillators 52C for the antenna
units 36Cb through 36Ce are allocated narrow frequency bands which
do not overlap, as denoted by f2 through f5 in FIG. 14. All these
frequencies f1 through f5 are within the specified frequency band
mentioned earlier, and are allocated to the antenna units 36Ca
through 36Ce so that the oscillation frequency for an antenna unit
is as different as possible from those for the adjacent antenna
units, as shown in FIG. 14.
In the controller 42C, a unit control circuit 60C is connected to
the modulation circuit 50C and reception circuit 56C of each of the
antenna units 36Ca through 36Ce, to output interrogatory signals at
a specified timing mentioned later, and to receive responding
signals. The unit control circuit 60C is connected to the signal
processor 44C through an interface circuit 62C. A power circuit 64C
is fed with power from an AC power supply (not shown). When power
is supplied, the power circuit 64C converts it to a specified DC
voltage, and applies the DC voltage to the unit control circuit 60C
and the interface circuit 62C, as well as to the antenna units 36Ca
through 36Ce.
In the tag unit 46C as a responding unit, an antenna 66C, composed
of a microstrip antenna formed on a PC board, is capable of
receiving a wide frequency range of radio waves as indicated by the
broken line in FIG. 14. Specifically, it is adapted to receive all
interrogatory signals with frequencies f1 through f5 output from
the antenna units 36Ca through 36Ce.
A control circuit 68C includes a CPU, ROM, RAM etc. It is designed
to receive interrogatory signals, and to output various data,
including the identification code, in the form of responding
signals to the interrogatory signals, according to the stored
program. The control circuit 68C is connected in two ways to the
antenna 66C: through a transmission circuit 70C, and through a
reception circuit 72C.
The transmission circuit 70C modulates the unmodulated carrier wave
received through the antenna 66C, by a responding signal output
from the control circuit 68C, and transmits the modulated wave. The
reception circuit 72C demodulates the radio wave received through
the antenna 66C, and inputs it as an interrogatory signal to the
control circuit 68C. The control circuit 68C is connected to
writable/readable nonvolatile memory data memory 74C. Each circuit
in the tag unit 46C is fed with power by a battery 76C.
The operation of the third invention is described below with
reference to FIGS. 15A to 15E, 16 and 17. The unit control circuit
60C of the controller 42C outputs interrogatory signals to the
antenna units 36Ca through 36Ce at the timings shown in FIG. 15.
Specifically, it outputs interrogatory signals to the antenna units
36Ca, 36Cc and 36Ce at the same timing with intervals of T1 as
shown in FIG. 15A, FIG. 15C and FIG. 15E, and to the antenna units
36Cb and 36Cd at the same timing with intervals of T1 but later by
T2 than the timing for the former three antenna units as shown in
FIGS. 15B and 15D.
In each of the antenna units 36Ca through 36Ce, the modulation
circuit 50C modulates the carrier wave from the oscillator 52C by
an interrogatory signal output from the controller 42C, and sends
it in the form of a microwave signal through the antenna 48C to the
appropriate communication area 38Ca through 38Ce.
In the interrogatory signal output interval T1, the period "ta" is
set for outputting an interrogatory signal, and the remaining
period "tb" for outputting a responding signal. For any two
adjacent antenna units, e.g., 36Ca and 36Cb, the interrogatory
signal output periods "ta" do not overlap.
The modulation circuit 50C of each antenna unit 36Ca through 36Ce
does not carry out modulation in the period "tb" when interrogatory
signals are not given from the controller 42C. During this period,
the carrier wave from the oscillator 52C is output unmodulated to
each of the communication areas 38Ca through 38Ce via the antenna
48C. In other words, each antenna unit 36Ca through 36Ce always
outputs radio waves, but transmits an interrogatory signal only
during the period "ta" which comes at intervals of T1.
With interrogatory signals being thus output to the communication
areas 38Ca through 38Ce, when an unmanned truck 30C, approaching
the gate 34C on the runway 32C, enters the communication area 38Ca,
the tag unit 46C communicates by the following method. The tag unit
46C receives radio waves by the antenna 66C. The reception circuit
72C demodulates the radio waves to an interrogatory signal, and
sends the signal to the control circuit 68C.
Determining that the interrogatory signal is from the antenna unit
36Ca, the control circuit 68C outputs a responding signal of the
identification code to the transmission circuit 70C. At this time,
the antenna 66C is receiving an unmodulated carrier wave from the
antenna unit 36Ca, and is sending it to the transmission circuit
70C. The transmission circuit 70C modulates this carrier wave by
the responding signal, and reflects the modulated carrier back for
transmission.
The antenna unit 36Ca receives the responding signal radio wave
through the antenna 48C, thereby identifying the tag unit 46C. More
specifically, the radio wave received by the antenna 48C is input
through the circulator 54C and the mixer 58C to the reception
circuit 56C, where it is demodulated to the responding signal and
sent to the controller 42C. The unit control circuit 60C of the
controller 42C then inputs the identification code data of the
communicating tag unit 46C through the interface circuit 62C to the
signal processor 44C.
To continue communicating with the tag unit 46C, the controller 42C
controls the antenna unit 36Ca to output an interrogatory signal
during the next interrogatory signal output period. If the
interrogatory signal includes a write command instructing the tag
unit 46C to store certain data, the control circuit 68C of the tag
unit 46C carries out the processing to write the data to the data
memory 74C. If the interrogatory signal includes a read command
instructing the tag unit 46C to read certain data, the control
circuit 68C of the tag unit 46C carries out the processing to read
the data from the data memory 74C, and output it for
communication.
Now the operation of the present invention is described for the
case in which the tag unit 46C of an unmanned truck 30C passes
through the overlapping zone 40Cc, between the communication area
38Cc of the antenna unit 36Cc and the communication area 38Cd of
the antenna unit 336Cd, as shown in FIG. 16. Since the
interrogatory signal output timing of the antenna unit 36Cd lags by
T2 behind that of the antenna unit 36Cc as described earlier, the
tag unit 46C in the overlapping communication zone 40Cc receives
the radio wave of an interrogatory signal from either the antenna
unit 36Cc or 36Cd.
The tag unit 46C may receive the radio wave of an interrogatory
signal from the antenna unit 36Cc first. The control circuit 68C of
the tag unit 46C accepts the signal, and outputs a responding
signal according to the process described above. The transmission
circuit 70C modulates, by responding signal, the unmodulated
carrier wave received from the antenna unit 36Cc through the
antenna 66C, and reflects it back for transmission. At the time of
responding signal transmission, the antenna 66C may receive an
interrogatory signal radio wave from the antenna unit 36Cd because
the tag unit 46C is positioned in the overlapping communication
zone 40Cc.
In such a case, the responding signal radio wave being transmitted
from the antenna 66C to the antenna unit 36Cc is also transmitted
to the antenna unit 36Cd, and the interrogatory signal from the
antenna unit 36Cd is modulated by a responding signal and
transmitted to both antenna units 36Cc and 36Cd. However, since the
frequencies of radio waves transmitted from the antenna units 36Cc
and 36Cd are set differently at f3 and f4, respectively, the
antenna unit 36Cc can receive and identify the radio wave of
responding-signal modulated carrier waves with a frequency of f3
alone. Furthermore, by including the identification code for each
of the antenna units 36Ca through 36Ce in each interrogatory
signal, and that for each tag unit 46C in each responding signal,
each antenna or tag unit that receives a signal can determine
whether the signal is intended for that antenna unit.
Thus, the tag unit 46C responds only to the interrogatory signal
from the antenna unit 36Cc--the signal received first --,
communicating with the antenna unit 36Cc. After completing
communication with the antenna unit 36Cc, if the tag unit 46C
remains in the overlapping zone 40Cc, it will accept the
interrogatory signal from the antenna unit 36Cd and communicate
with it. Therefore, the tag unit 46C can communicate with the
antenna units 36Cc and 36Cd accurately, without radio interference
between the antenna units.
Furthermore, since the communication time is not divided between
the antenna units 36Cc and 36Cd as it is for conventional
time-sharing communication, each antenna unit is not limited in
communication time. Consequently, even when the unmanned truck 30C
is moving at high speed in the overlapping communication zone 40Cc,
the tag unit 46C has sufficient communication time to be identified
by the antenna unit 36Cc or 36Cd.
In the overlapping communication zone 40Cc, the tag unit 46C
communicates with both antenna units 36Cc and 36Cd, and upon
completing communication with either of the antenna units, it stops
communicating with the other unit. Accordingly, when the unmanned
truck 30C is moving on the runway 32C, passing through the
communication area 38Cc, the overlapping zone 40Cc and the
communication area 38Cd, in the direction indicated by the arrow in
FIG. 17, the tag unit 46C keeps communicating with both antenna
units 36Cc and 36Cd, without interruption due to change in the
communication area. By maintaining communication with both antenna
units 36Cc and 36Cd, the tag unit 46C can always exchange signals
with either of the antenna units 36Cc and 36Cd until it completes
communication. When completing communication with either of the
antenna units 36Cc and 36Cd, the tag unit 46C stops communicating
with the other antenna unit 36Cc or 36Cd, as mentioned earlier, to
prevent duplicate data writing; if duplicate data writing is not
anticipated, it is not necessary to stop communicating with the
other antenna unit.
Thus, according to the above embodiment of the third invention,
while the five antenna units 36Ca through 36Ce, providing
communication areas 38Ca through 38Ce, respectively, are set with
the communication areas of the adjacent antenna units overlapping,
the oscillators 52C of the five antenna units 36Ca through 36Ce are
allocated with different narrow bands of oscillation frequencies f1
through f5, and the controller 42C controls the antenna units 36Ca
through 36Ce so that adjacent antenna units provide overlapping
communication zones 40Ca through 40Cd output interrogatory signals
at different timings, with the time lag T2. As a result, each of
the antenna units 36Ca through 36Ce can communicate accurately and
promptly with the tag unit 46C of an unmanned truck 30C passing
through the respective communication areas.
In the above embodiment, the antenna units 36Ca through 36Ce are
positioned so that the communication areas of adjacent antenna
units overlap. Alternatively, the antenna units 36Ca through 36Ce
may be positioned so that the communication areas of three or more
of the antenna units overlap. In such a case as well, communication
can be accurate, without any radio interference, if the antenna
units 36Ca through 36Ce are controlled to output interrogatory
signals at different timings.
In the above embodiment, the third invention is applied to an
unmanned truck identification system. The invention is applicable
to other mobile object identification system as well, including
factory process control system for control of products in the
production line, and in systems for managing room entry/exit.
Before the fourth and fifth inventions are explained, the
conventional arts as opposed to the fourth and fifth inventions and
their problems will be detailed in the following.
Presently, a vehicle is identified from the exterior by the license
plates attached to its front and rear (or to the rear alone for a
two-wheeled vehicles), from the mandatory vehicle inspection label
to be updated three years after purchase and thereafter every two
years in general, and from the regular inspection and maintenance
label indicating that the vehicle has undergone regular inspection
and maintenance. These labels are often attached to the inside of
the front windshield. All of the above information for identifying
the vehicle is checked visually. When a vehicle is moving, it is
difficult to check the above information visually, particularly at
night.
A non-contact information card is conventionally known as means for
radio communication. When this information card is used in a
vehicle, the driver holds up the card to face it toward an
interrogator or other information reader, or places it on the
dashboard, to communicate with the interrogator. If this
information card retains vehicle identification data such as the
frame number stamped on the frame of each vehicle, the vehicle
registration number shown on the license plate, and the expiration
date of the mandatory inspection certificate, the information card
could be used to provide the identifying information specific to
each vehicle.
In such applications, however, since the information card is not
fixed to the vehicle, it can be taken and used for other vehicles.
Consequently, the information stored in the information card does
not always conform to the identifying information specific to the
vehicle for which the card is being used. Such information card is
therefore not practical in view of its high potential for
abuse.
The fourth invention has solved the above problem. An embodiment of
the fourth invention is described below. FIG. 20 is a general view
of the electronic mandatory inspection label 1D according to an
embodiment of the fourth invention. The electronic mandatory
inspection label 1D is roughly divided into a visible information
layer 2Da and an electronic circuitry layer 2Db, which are joined
with adhesive so as not to be easily separable. The visible
information layer 2Da may be made of paper, with printed
information, including a figure indicating the month of expiration
of the mandatory inspection certificate. The electronic circuitry
layer 2Db incorporates a responding circuit 3D which sends and
receives electronic information.
The electronic mandatory inspection label 1D is fixed to the front
windshield 7Da of a vehicle 7D, as shown in FIG. 21, using adhesive
so that it cannot be removed, or using an appropriate
change-preventive material that leaves clear evidence of removal.
The electronic mandatory inspection label 1D communicates with
interrogators 8D (described later) installed along a road.
The most preferable fixing position of the electronic mandatory
inspection label 1D is, as shown in FIG. 21, the upper center of
the front windshield 7Da, just behind the rearview mirror RM, as
viewed from the driver's seat. In this position, the label does not
obstruct the driver's view. In addition, this position is outside
the moving range (indicated by the chain double-dashed lines in
FIG. 21) of the windshield wiper arms WP, so that the metal used in
the wiper arms has minimal influence on communication between the
responding circuit 3D and an interrogator 8D.
The construction of the responding circuit 3D is now described in
detail, with reference to FIG. 22. The responding circuit 3D
comprises an IC chip 21D for processing internal information, an
antenna 22D for receiving interrogatory signals S1 and transmitting
responding signals S2, and a built-in battery 23D for driving the
IC chip 21D.
The IC chip 21D comprises a detector 21Da, a level comparator 21Db,
a memory 21Dc, a central processing unit (hereinafter referred to
as the CPU) 21Dd, a clock generator 21De, and a modulator 21Df. The
detector 21Da detects information in an interrogatory signal S1
received by the antenna 22D. The level comparator 21Db confirms
reception of the interrogatory signal based on the signal level
data sent from the detector 21Da, and supplies power to each
circuit. The memory 21Dc stores vehicle information such as a frame
number, data on the mandatory inspection certificate expiration,
and a vehicle registration number (license plate number). When the
CPU 21Dd receives power from the level comparator 21Db, it
transmits a signal according to the information stored in the
memory 21Dc. The clock generator 21De generates clock pulses to
operate the CPU 21Dd. The modulator 21Df modulates the
interrogatory signal S1 using the signal output from the CPU 21Dd,
and transmits it as a responding signal S2 through the antenna
22D.
An interrogatory signal S1 sent from an interrogator 8D is received
by the responding circuit 3D through the antenna 22D. Receiving
this signal, the level comparator 21Db starts to supply power to
the CPU 21Dd and to the clock generator 21De. Then, the CPU 21Dd
interprets and executes the command contained in the interrogatory
signal S1. If the command demands internally stored data, the CPU
21Dd operates to modulate the interrogatory signal S1 by the
information stored in the memory 21Dc and to transmit it as an
internal-information-bearing responding signal S2 through the
antenna 22D.
Now, the following paragraphs describe an interrogator 8D which
outputs radio waves to the responding circuit 3D to obtain vehicle
information.
The means of the interrogator 8D is to transmit interrogatory
signals S1 to, and receive responding signals S2 from, the
above-mentioned electronic mandatory inspection label 1D. As shown
in FIG. 23, the interrogator 8D comprises: a carrier generation
circuit 11D to generate a carrier wave; a modulator 12D to produce
an interrogatory signal S1 by superposing information on the
carrier wave; a circulator 13D to separate transmission waves from
received waves; an antenna 14D as the entrance and exit of
electromagnetic waves; a demodulator 15D to detect information in
the received waves of a responding signal S2; a signal processor
16D to control the modulator 12D and demodulator 15D to process
information; and an external interface 17D which communicates
necessary information of the received responding signal S2 to an
upper information processing system (such as the system management
computer 30D shown in FIG. 25).
The signal processor 16D is composed of a CPU 16Da which includes
programs to control communication, and a system-identifying
information setting block 16Db which sets the identification number
for the system. This block 16Db is composed of a PROM 16Dc to store
system-identifying information.
Having the circuitry construction mentioned above, the interrogator
8D operates as follows.
An interrogatory signal S1 to be transmitted from the interrogator
8D is produced in the modulator 12D by modulating the carrier wave
from the carrier wave generation circuit 11D. In other words, the
data sent from the signal processor 16D to the modulator 12D is
superposed on the interrogatory signal S1. The interrogatory signal
S1 thus produced is sent through the circulator 13D, and is
radiated into the air through the antenna 14D.
When a responding signal S2 is returned from the responding circuit
3D of the electronic mandatory inspection label 1D, the
interrogator 8D receives it by the antenna 14D. The responding
signal S2 is then input through the circulator 13D to the
demodulator 15D, which extracts information from the responding
signal S2 and gives the information to the signal processor 16D.
The signal processor 16D processes the information, and outputs it,
if necessary, to the external interface 17D. The signal processor
16D also carries out internal processing based on the control
instruction and various other information input from the external
interface 17D, and sends transmission data to the modulator
12D.
Using the above-mentioned electronic mandatory inspection label 1D
and interrogator 8D, it is possible to realize the systems given
below:
(1) Toll road accounting system (FIG. 24)
When an ordinary vehicle B approaches a toll gate T on a toll road
TR, the vehicle B is required to run along the first lane R1 and
stop in front of the toll booth 27D to pay the toll to a collecting
person P.
Meanwhile, when a vehicle A bearing the electronic mandatory
inspection label 1D approaches the toll gate T, it has only to run
along the second lane R2 to pay the toll; the interrogator 8D
installed above the second lane R2 reads the frame number and other
vehicle information from the electronic mandatory inspection label
1D of the vehicle A, and judges the vehicle A admissible to the
road, based on the information registered in the system management
computer (not shown). In this case, the toll may be paid from the
designated bank account on a later day. If read information is
stored in a database, it is possible to obtain monthly data on how
many times each vehicle has passed the toll gate T, thus enabling
the system to give toll discounts to vehicles frequently using the
toll road.
(2) Incoming/outgoing vehicle management system of a parking lot
(FIG. 25)
When a vehicle C bearing the electronic mandatory inspection label
1D enters a parking lot, the interrogator 8D installed at the upper
part of the entrance reads the frame number and other vehicle
information of the vehicle C from the electronic mandatory
inspection label 1D. The vehicle information read by the
interrogator 8D is input to the system management computer 30D
connected with the interrogator 8D. If the frame number of the
vehicle C has been registered as a customer of the parking lot, the
computer 30D judges the vehicle C as a customer, based on the input
information, and opens the barrier gate 32D.
The vehicle C is thus allowed to enter the parking lot without
paying the parking charge at the entrance. The charge may be paid
from the designated bank account on a later day as in the case of
the toll road accounting system. If read information is stored in a
database, it is possible to obtain monthly data on how many times
each vehicle has used the parking lot, thus enabling the system to
give discounts on parking charges to vehicles frequently using the
parking lot.
(3) Regular customer sensing system (FIG. 26)
When a vehicle D bearing the electronic mandatory inspection label
1D is to enter the parking lot of a department store, the
interrogator 8D installed at the entrance reads the vehicle
information from the label 1D. If the vehicle information indicates
that the visitor is a special regular customer, the system may show
a vacant parking space number on the guideboard 41D, and inform the
special customers section of the visit of the special regular
customer by displaying such on the indication board 45D, thus
enabling a person in charge to meet the customer promptly.
(4) Illegal parking control by the police
In controlling illegal parking, the police can collect vehicle
information (frame numbers, license plate numbers etc.) using a
portable handy terminal that incorporates the interrogator 8D. This
tool eliminates the need to fill out documents with pens, allowing
each policeman to control a large number of illegally parking
vehicles efficiently in a short period of time.
(5) Control by the police of vehicle mandatory inspection
certificate expiration
By installing the interrogator 8D above or on the side of roads,
the police can control vehicles whose mandatory inspection
certificates have expired. With radio waves transmitted to each
oncoming vehicle, the interrogator 8D reads at least the frame
number and the expiration date of the mandatory inspection
certificate from the electronic mandatory inspection label 1D
attached to the vehicle. Based on the information thus read, the
police can find illegal vehicles. Conventionally, to find such
illegal vehicles, policemen have been required to visually read the
month of expiration on each mandatory vehicle inspection label 55D
(FIG. 27). The present application of the fourth invention relieves
policemen from such troublesome and inefficient work, and is very
effective because it enables the police to obtain vehicle
information easily, even from a moving vehicle.
(6) Criminal investigation by the police
In criminal investigation, the police may be required to detect an
escaping vehicle. The electronic mandatory inspection label 1D can
be applied to this purpose. In such application, the interrogators
8D are installed at important points of cities, so that information
on the escaping vehicle can be obtained and referred to for
pursuit. Conventionally, investigators have been required to
identify visually the characteristic and license plate number of
the escaping vehicle. The present invention eliminates the need for
such visual identification, and is very effective because it
enables the police to identify the vehicle in question easily, even
if the vehicle is moving.
The electronic label for a vehicle according to the fifth invention
is described in the following.
FIG. 27 is a general view of the front windshield 51D, as viewed
from inside the vehicle, which incorporates the responding circuit
53D of the electronic label for a vehicle according an embodiment
of the fifth invention. The responding circuit 53D is integral with
a power line 57D, and is embedded in the front windshield 51D. The
power line 57D is passed through the front windshield 51D, and
connected to an on-board battery 59D.
The responding circuit 53D is embedded in the front windshield 51D
at a position, for example, behind the rearview mirror RM, where
the mandatory vehicle inspection label 55D is attached. Concealed
by the mirror RM and the mandatory vehicle inspection label 55D,
the responding circuit 53D is not visible from the driver's seat.
Preferably, the responding circuit 53D is located in the upper
center of the front windshield 51D and outside the moving range
(indicated by the chain double-dashed lines in FIG. 27) of the
windshield wiper arms WP, for the same reason as mentioned for the
electronic mandatory inspection label 1D of the fourth
invention.
More preferably, the mandatory vehicle inspection label 55D should
be attached to the front windshield 51D in such a position that the
upper end portion of the label 55D is laid over the responding
circuit 53D, so that the necessary information, including the
figure indicating the expiring month on the label 55D is visible,
and that the responding circuit 53D is hidden behind the label
55D.
The responding circuit 53D of the fifth invention is of the same
construction as the responding circuit 3D of the electronic
mandatory inspection label 1D, except that the former circuit 53D
does not have a built-in battery 23D. Specifically, as shown in
FIG. 28, it comprises an antenna unit 61D for transmitting and
receiving radio waves, an IC chip 62D for processing internal
information, and a power line 57D for supplying power to drive the
IC chip 62D, all arranged on a transparent PET substrate 60D.
FIG. 29 shows another general view of the front windshield 51D, as
viewed from the inside of a vehicle, in which the responding
circuit 53D is connected to another information processor 70D,
which may be an IC card reader/writer. In this case, as shown, the
responding circuit 53D is integrally connected with a
communication/power line 57D, and is embedded in the front
windshield 51D. The communication/power line 77D is passed through
the front windshield 51D and connected to the information processor
70D, which is connected to the on-board battery 59D. An IC card, a
floppy disc, a reloadable optical disc (compact disc), or any other
reloadable tool may be used as information processing media for the
information processor 70D.
Some methods of embedding the responding circuit 53D in the front
windshield 51D will be described with reference to FIGS. 30A to
30C. FIGS. 30A and 30B show a method applicable when the front
windshield is of laminated glass. In the process of manufacturing
the laminated glass, the responding circuit 53D is sandwiched
together with a resin sheet 51Db between a top glass sheet 51Da and
a bottom glass sheet 51Dc. FIG. 30C shows another method. A recess
is formed inside the front windshield 51D, and the power line 57D
or communication/power line 77D is passed through the glass to a
position under the recess. Then, the responding circuit 53D is set
in the recess so that the electrodes of the circuit 53D come in
contact with the power line 57D or communication/power line 77D. A
glass cover 51Dd is placed over the responding circuit 53D, and
fixed to the front windshield 51D using adhesive 51De. By either of
the above methods, it is possible to integrally incorporate the
responding circuit 53D into the front windshield 51D (or in other
words, into a vehicle body).
If the responding circuit 53D of the fifth invention incorporated
into the front windshield 51D is mounted on a vehicle, it is also
very effectively applicable to the toll road accounting system, the
incoming/outgoing vehicles management system of a parking lot, the
regular customer sensing system, the control by police of illegal
parking or expiration of the vehicle mandatory inspection
certificate, criminal investigation by the police etc., as is the
electronic mandatory inspection label 1D of the fourth
invention.
The operation of the fifth invention in application as a toll
accounting system of FIG. 24 is described in the following. If the
responding circuit 53D is connected to an IC card reader/writer as
the information processor 70D, as shown in FIG. 29, and if the IC
card has a prepaid means, the information that the vehicle A has
been judged admissible to the toll road is sent through the
communication/power line 77D to the IC card reader. The IC card
then deducts one point from the number of prepaid points, thereby
paying the toll. If the IC card has a credit means, after vehicle A
has been judged admissible, the credit number is output from the IC
card to the responding circuit 53D. The responding circuit 53D
communicates the credit number to the interrogator 8D, to pay the
toll on credit.
In the application to the incoming/outgoing vehicle management
system of a parking of FIG. 25 as well, if the responding circuit
53D is connected with the IC card reader/writer to enable the
interrogator 8D to read the credit number, the driver can pay the
parking charge on credit.
In the embodiment described above, the responding circuit 53D is
located in the position where the vehicle mandatory inspection
label 55D is attached, as shown in FIG. 27. The responding circuit
53D may be positioned in the upper left corner of the front
windshield 51D, where the regular check and maintenance label 56D
is attached as shown in FIG. 27. In this position as well, the
responding circuit 53D is outside the moving range (indicated by
the chain double-dashed lines in FIG. 27) of the windshield wiper
arms WP.
In the present embodiment of the fifth invention, the responding
circuit 53D is embedded in the front windshield, for convenience in
communicating with an interrogator 8D and on the assumption that
vehicles normally move forward. The responding circuit 53D can be
embedded in the rear windshield or a window glass without affecting
the spirit of the invention. However, considering that the
invention is applied to various police control systems, as
mentioned above, the responding circuit 53D should not be built
into movable window glass for the following reason: if the window
glass containing the responding circuit 53D has been moved into the
side panel to open the window, the metal of the side panel hampers
communication between the responding circuit 53D and the
interrogator 8D.
According to the present embodiment of the fifth invention,
transparent PET is used for the substrate of the responding circuit
53D, as shown in FIG. 28. Other material, such as resin and glass,
may be used instead of PET as long as it is transparent.
Now, a second embodiment of the fifth invention concerning the
responding-circuit-incorporating windshield 51D is described in the
following. FIG. 31 shows the electrical construction of the second
embodiment. As shown, the second embodiment comprises an antenna
101D, an information processor 104D, a shield wire 107D connecting
the antenna 101D with the information processor 104D, a power
supply 106D, and an actuator 105D. The information processor 104D
is composed of an RF processing IC 102D and a reader/writer
(hereinafter referred to as R/W) 103D which exchanges data with the
RF processing IC 102D.
The R/W 103D may be an IC card R/W or a magnetic card R/W. For the
shield wire 107D, a shielded wire, not an ordinary wire, is used to
protect the system from noise generated between the antenna 101D
and the RF processing IC 102D. The actuator 105D is, for example, a
driver's seat position adjusting motor, or a door-mirror angle
adjusting motor.
More specifically, the antenna 101D is embedded in the front
windshield 111D at a position behind the rearview mirror RM, where
the mandatory vehicle inspection label 55D is attached, or at a
position where the regular check and maintenance label 56D is
attached, so that it does not obstruct the driver's view, as shown
in FIG. 32. The antenna 101D is connected to the information
processor 104D housed in the dashboard, by the shield wire 107D
laid around the front windshield 111D.
As shown in FIG. 33, the RF processing IC 102D of the information
processor 104D includes two different memories 113D: an EEPROM 114D
whose data can be rewritten electrically but cannot be erased or
changed by ON/OFF of power supply or by ultraviolet ray radiation;
and an SRAM 115D whose data can be reset (erased) by ON/OFF of
power supply. The identifying information specific to a vehicle,
such as the license plate number, and the expiration date of the
mandatory inspection certificate, is stored in the EEPROM 114D.
Information on an individual person such as the person's
identification number for a membership athletic club; and the
registration number for the toll road accounting system of FIG. 24
or for a particular parking space of the incoming/outgoing vehicle
management system of a parking lot (FIG. 25) is stored in either
the SRAM 115D or the EEPROM 114D. The information processor 104D is
equipped with a ten-key board so that individual information can be
called from the EEPROM 114D by inputting the appropriate code
number.
The operation of the second embodiment of the fifth invention is
described in the following.
When the relevant vehicle is registered, the vehicle registration
number, the expiration date of the mandatory inspection certificate
and other data specific to the vehicle are input to the EEPROM 114D
of the RF processing IC 102D. Such data can be input to the EEPROM
114D through the R/W 103D by using an IC card or a magnetic card,
or through the antenna 101D embedded in the front windshield 111D
by sending radio waves to the antenna 101D. The data thus input can
be changed only by officials of the Land Transportation Bureau at
the time of vehicle mandatory inspection or reregistration, and
cannot be changed by other individuals.
Prior to using the vehicle for the first time, the driver is
expected to input the individual information to the EEPROM 114D of
the memory 113D, by inserting an IC card or magnetic card into the
information processor 104D (R/W 103D) housed in the dashboard. At
that time, the driver is also expected to register code numbers.
The individual information thus stored is not erased by turning the
power supply or the engine on or off, and can be called up as
desired by inputting the appropriate code number. Accordingly, the
driver need not carry his/her IC card or magnetic card. In
addition, it is not necessary for the driver to input the
individual information each time the vehicle is used.
In actual operation, when the vehicle engine is started, the
vehicle-specific information stored in the EEPROM 114D, that is,
the license plate number and the expiration date of the mandatory
inspection certificate, are unconditionally input to the SRAM 115D.
When a code number is input, the individual information as opposed
to the code number is also uploaded. As the vehicle in this state
is passing in front of the interrogator 8D of the system shown in
FIG. 24 or 25, the interrogator 8D receives the information stored
in the SRAM 115D from the antenna 101D embedded in the vehicle.
The information received by the interrogator 8D is input to the
host computer (not shown) of the system for necessary processing.
When the interrogator 8D transmits information, it is received by
the antenna 101D of the vehicle, and written in the EEPROM 114D of
the information processor 104D when necessary.
When the engine is stopped, the power supply 106D is turned off,
and the information in the SRAM 115D of the RF processing IC 102D
is erased while the information stored in the EEPROM 114D remains
unerased.
In the above second embodiment of the fifth invention, the RF
processing IC 102D is installed in the information processor 104D
housed in the dashboard. Alternatively, it may be embedded together
with the antenna 101D in the front windshield 111D. In that case,
the shield wire 107D is not necessary.
In the above second embodiment, code numbers are used to call up
individual information. Other means, such as a magnetic card, IC
card, and collation of fingerprints, may be used to this end, as
long as it enables the driver to confirm the information specific
to the vehicle.
In the above second embodiment, the antenna 101D is embedded in the
front windshield 111D. It may be attached to the inside of the
front windshield 111D. The information processor 104D may be
equipped with a display to show the content of communication. The
R/W 103D may be an optical card R/W instead of an IC or magnetic
card R/W.
The embodiments of the first through the fifth inventions have been
described independently in the above paragraphs. Needless to say,
the mobile object identification system is realized by combining
the first through the fifth inventions.
INDUSTRIAL APPLICABILITY OF THE INVENTION
According to the first invention, as described above, if the
responder for the mobile object identification system receives a
write signal from a writing interrogator, with the write completion
status stored, the control means invalidates the write signal.
Consequently, the responder writes data only once as it passes
through the communication area of the writing interrogator. Thus,
despite its simple construction, the first invention is effective
in preventing duplicate data writing.
According to the second invention, the interrogator of the
communication complex for the mobile object identification system
includes a level judging circuit to identify the highest level
responding signal of those received by the stationary antenna, and
a signal selection circuit to selectively output to the control
device the responding signal identified by the level judging
circuit. With the communication complex according to the second
invention, therefore, it is not necessary to switch over the
multiple antennas of the interrogator to communicate with the
responder. In other words, the second invention provides such a
superior effect that it allows the responder to complete
communicating with the interrogator without interruption.
With the mobile object identification equipment according to the
third invention, the control means controls the plurality of
interrogators so that at least those interrogators whose
communication areas overlap provide different-frequency carrier
waves and transmit interrogatory signals at different timings.
Therefore, even in the overlapping zone of communication areas,
there is no need to divide interrogator output signals
communication time, and there is no possibility that the responder
receives two interrogatory signals at a time. Thus, the third
invention provides such superior effects that it prevents radio
interference and promises accurate and prompt communication even
when the responder is moving at high speed.
When the electronic label for the mobile object identification
system according to the fourth or fifth invention is attached to or
embedded in a vehicle, and when an interrogatory signal is sent
from an external interrogator to the vehicle, the responding
circuit receives the interrogatory signal and sends back
appropriate vehicle information stored in advance in the responding
circuit. Therefore, it is not necessary for persons to identify
vehicle information visually. In addition, the vehicle information
can be identified easily even when the vehicle is moving. If the
electronic label bears on its surface the information provided on
the particular labels legally required to be attached to the front
windshield of a vehicle, the electronic label can be attached to
the front windshield without causing any problems. As well, the
electronic label bearing such information on the surface is not
expected to be removed from the vehicle. Accordingly, the
information read from the electronic label may be reasonably
considered as information specific to the vehicle.
Thus, with the electronic label according to the fourth or fifth
invention, the vehicle-related information, such as the frame
number and the expiration date of the mandatory inspection
certificate, can be collected by the interrogator by non-contact
means, and not visually. Therefore, the fourth or fifth invention
is extremely effective if applied to the toll or parking charge
collecting system, illegal vehicle or illegal parking control by
the police, criminal investigation by the police etc.
* * * * *